The present invention relates to a speaker used in a portable communication equipment such as a portable telephone and other equipments.
Referring to FIG. 6 showing a conventional speaker, a yoke 2 made of magnetic material is embedded in a case 1 made of plastic by insert molding. A permanent magnet 3 is secured to the yoke 2, and a top plate 4 made of magnetic material is adhered to the magnet 3 to form a magnetic circuit and to form a magnetic gap between the top plate 4 and the yoke 2.
A diaphragm 6 is secured to the case 1 at a shoulder 1b of the periphery thereof. A voice coil 5 secured to the underside of the diaphragm 6 is inserted in the magnetic gap. A protector 7 made of metal is secured to the case 1, interposing the diaphragm 6. A plurality of sound discharge holes 7a are formed in the protector 7. The diaphragm 6 and the protector 7 are positioned by a cylindrical peripheral projection 1a. 
A pair of ends 9 of the voice coil 5 are outwardly extended from the case 1 passing through a groove 1c formed in a peripheral wall of the case. On the underside of the case 1, a substrate 8 made of plastic is adhered, and a pair of terminal plates 10 are secured to the substrate 8. Each of ends 9 is connected to one of the terminal plate 10 by solder 11. The terminal plate 10 is connected to a circuit of the equipment to be mounted therein.
Thus, when a signal current is applied to the voice coil 5 through the terminal plates 10, the diaphragm 6 vibrates to produce sounds.
In the above described conventional speaker, the diaphragm 6 is positioned by the peripheral projection 1a and secured to the shoulder 1b. Therefore, the effective diameter dφ of the diaphragm 6 is reduced by double of width of the peripheral projection 1a. The reduction of the diameter of the diaphragm causes the quality of the produced sound to deteriorate.
On the other hand, there are problems in manufacturing of the speaker. In the manufacturing, after the diaphragm 6 and the protector 7 are secured to the shoulder 1b the case 1 is inverted in order to solder the ends 9 to terminal plates 10. However, the inverting operation of the case causes the manufacturing operation of the speaker to complicate.